source: josm/trunk/src/org/tukaani/xz/lzma/LZMACoder.java@ 13472

Last change on this file since 13472 was 13350, checked in by stoecker, 6 years ago

see #15816 - add XZ support
File size: 4.2 KB
Line 
1/*
2 * LZMACoder
3 *
4 * Authors: Lasse Collin <lasse.collin@tukaani.org>
5 * Igor Pavlov <http://7-zip.org/>
6 *
7 * This file has been put into the public domain.
8 * You can do whatever you want with this file.
9 */
10
11package org.tukaani.xz.lzma;
12
13import org.tukaani.xz.rangecoder.RangeCoder;
14
15abstract class LZMACoder {
16 static final int POS_STATES_MAX = 1 << 4;
17
18 static final int MATCH_LEN_MIN = 2;
19 static final int MATCH_LEN_MAX = MATCH_LEN_MIN + LengthCoder.LOW_SYMBOLS
20 + LengthCoder.MID_SYMBOLS
21 + LengthCoder.HIGH_SYMBOLS - 1;
22
23 static final int DIST_STATES = 4;
24 static final int DIST_SLOTS = 1 << 6;
25 static final int DIST_MODEL_START = 4;
26 static final int DIST_MODEL_END = 14;
27 static final int FULL_DISTANCES = 1 << (DIST_MODEL_END / 2);
28
29 static final int ALIGN_BITS = 4;
30 static final int ALIGN_SIZE = 1 << ALIGN_BITS;
31 static final int ALIGN_MASK = ALIGN_SIZE - 1;
32
33 static final int REPS = 4;
34
35 final int posMask;
36
37 final int[] reps = new int[REPS];
38 final State state = new State();
39
40 final short[][] isMatch = new short[State.STATES][POS_STATES_MAX];
41 final short[] isRep = new short[State.STATES];
42 final short[] isRep0 = new short[State.STATES];
43 final short[] isRep1 = new short[State.STATES];
44 final short[] isRep2 = new short[State.STATES];
45 final short[][] isRep0Long = new short[State.STATES][POS_STATES_MAX];
46 final short[][] distSlots = new short[DIST_STATES][DIST_SLOTS];
47 final short[][] distSpecial = { new short[2], new short[2],
48 new short[4], new short[4],
49 new short[8], new short[8],
50 new short[16], new short[16],
51 new short[32], new short[32] };
52 final short[] distAlign = new short[ALIGN_SIZE];
53
54 static final int getDistState(int len) {
55 return len < DIST_STATES + MATCH_LEN_MIN
56 ? len - MATCH_LEN_MIN
57 : DIST_STATES - 1;
58 }
59
60 LZMACoder(int pb) {
61 posMask = (1 << pb) - 1;
62 }
63
64 void reset() {
65 reps[0] = 0;
66 reps[1] = 0;
67 reps[2] = 0;
68 reps[3] = 0;
69 state.reset();
70
71 for (int i = 0; i < isMatch.length; ++i)
72 RangeCoder.initProbs(isMatch[i]);
73
74 RangeCoder.initProbs(isRep);
75 RangeCoder.initProbs(isRep0);
76 RangeCoder.initProbs(isRep1);
77 RangeCoder.initProbs(isRep2);
78
79 for (int i = 0; i < isRep0Long.length; ++i)
80 RangeCoder.initProbs(isRep0Long[i]);
81
82 for (int i = 0; i < distSlots.length; ++i)
83 RangeCoder.initProbs(distSlots[i]);
84
85 for (int i = 0; i < distSpecial.length; ++i)
86 RangeCoder.initProbs(distSpecial[i]);
87
88 RangeCoder.initProbs(distAlign);
89 }
90
91
92 abstract class LiteralCoder {
93 private final int lc;
94 private final int literalPosMask;
95
96 LiteralCoder(int lc, int lp) {
97 this.lc = lc;
98 this.literalPosMask = (1 << lp) - 1;
99 }
100
101 final int getSubcoderIndex(int prevByte, int pos) {
102 int low = prevByte >> (8 - lc);
103 int high = (pos & literalPosMask) << lc;
104 return low + high;
105 }
106
107
108 abstract class LiteralSubcoder {
109 final short[] probs = new short[0x300];
110
111 void reset() {
112 RangeCoder.initProbs(probs);
113 }
114 }
115 }
116
117
118 abstract class LengthCoder {
119 static final int LOW_SYMBOLS = 1 << 3;
120 static final int MID_SYMBOLS = 1 << 3;
121 static final int HIGH_SYMBOLS = 1 << 8;
122
123 final short[] choice = new short[2];
124 final short[][] low = new short[POS_STATES_MAX][LOW_SYMBOLS];
125 final short[][] mid = new short[POS_STATES_MAX][MID_SYMBOLS];
126 final short[] high = new short[HIGH_SYMBOLS];
127
128 void reset() {
129 RangeCoder.initProbs(choice);
130
131 for (int i = 0; i < low.length; ++i)
132 RangeCoder.initProbs(low[i]);
133
134 for (int i = 0; i < low.length; ++i)
135 RangeCoder.initProbs(mid[i]);
136
137 RangeCoder.initProbs(high);
138 }
139 }
140}
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